Wikipedia is the largest encyclopedia worldwide and is frequently updated by thousands of collaborators. A large part of the knowledge in Wikipedia is not static, but frequently updated, e. g., political events or new movies. This makes Wikipedia an extremely rich, crowdsourced information hub for events. However, currently there is no structured and standardised way to access information on those events and it is cumbersome to lter and enrich them manually. We have created a dataset based on a live extraction of Wikipedia, which performs this task via rules for ltering and ranking updates in DBpedia Live.
Since 2007, the DBpedia project has been extracting metadata and structured
data from Wikipedia and made it publicly available as RDF triples [
However, currently there is no structured and standardised way to access
information about these events and it is cumbersome to lter and enrich them
manually. While there are previous e orts to extract events from Wikipedia such
as [
The most important challenges when extracting events from DBpedia are (i) detecting events, (ii) providing context, and (iii) ranking events according to their importance. Since by far not all changes in Wikipedia are events, we need a mechanism to detect those. In our case, we rely on a semi-automatic approach
Wikipedia extract
DBpedia Live
Digest Templates
Changesets
SPARQL Endpoint (1) transform GUO model (2) query
(3) contextQuery Digest Items
Snapshots based on extensible rule sets, which are executed over DBpedia Live changesets. If a rule res, it triggers another query obtaining contextual information. The detected event is ranked according to the resource's PageRank and the edit activity of the Wikipedia page. The output of the processing pipeline is stored in RDF preserving all provenance information. 2
4 http://live.dbpedia.org/changesets/ 5 http://purl.org/hpi/guo# dbo:Organisation and having a label. More complex restrictions that can be expressed with SPARQL may apply. The dig:descriptionTemplate is used to generate a natural language headline for the detected event by substitution of the placeholders (enclosed in %%) with the respective resource labels.
Listing 1.1. The PRESIDENT digest template 2 3 4 5 6 7 8 9 10 1 dig : PRESIDENT a dbe : DigestTemplate ; dcterms : identifier " PRESIDENT " ; dcterms : description """ President changed ."""@ en ; dbe : queryString """ SELECT ?u ? res ? oldPres ? newPres { ?u guo : target_subject ? res ; guo : delete [ dbo : president ? oldPres ] ; guo : insert [ dbo : president ? newPres ] . }""" ; dbe : contextQueryString """ SELECT ? label
{ %% res %% a dbo : Organisation ; rdfs : label ? label . }""" ; dbe : descriptionTemplate """ %% newPres %% succeeds %% oldPres %% as the ,! president of %% res %%. """ .
From the validated result the nal event or so-called Digest Item is created. These items contain all necessary information to understand the change that occurred in DBpedia Live.
Listing 1.2. An event created from the LEADER template 1 item :2015/04/25/ Christian_Democrats_ ( Sweden ) - LEADER a dbe : Event ; 2 dbe : context snapshot :2015/04/25/ Christian_Democrats_ ( Sweden ) ; 3 dbe : update update :2015/04/25/ Christian_Democrats_ ( Sweden ) ; 4 dcterms : description """ Ebba Busch succeeded Goran Hagglund as the leader of ,! Christian Democrats ( Sweden )."""@ en ; 5 dbe : rank 1.82421 e -06 ; 6 prov : generatedAtTime " 2015 -04 -30 T13 :45:35.798+02:00 " ^^ xsd : dateTime ; 7 prov : wasDerivedFrom dig : LEADER , 8 changesets :2015/04/25/14/000201. removed . nt . gz , 9 changesets :2015/04/25/14/000201. added . nt . gz .
3
The dataset consists of daily digest dump les, which contain the descriptions of events (c.f. Listing 1.2) occurring on this day as well as the resource updates related to them. The resource snapshots that are linked in the event descriptions might be relevant for further investigation. Thus, they are kept separately in individual snapshot dumps. The daily generated event dumps can be accessed at http://events.dbpedia.org/dataset/ and additionally a SPARQL interface is o ered at http://events.dbpedia.org/sparql for querying the full dataset. The resource snapshots corresponding to the events are published in a separate path at http://events.dbpedia.org/snapshot/.
At the current stage 12 digest templates have been de ned and red6. Table 1 shows the number of events that matched the templates. 4
This paper presents an automated means to detect events and extract relevant data changes within DBpedia Live on the one hand, and on the other hand make these events available as Linked Data for others to consume and build upon. 6 De ned digest templates: http://events.dbpedia.org/data/digests.ttl.
Count Template Count Template 4509 AWARDED 146 LEADER 3252 HEADHUNTED 118 PODIUM 2539 RELEASED 89 PRESIDENT 1991 JUSTMARRIED 22 VOLCANO 785 DEADPEOPLE 7 EUROPE2015 782 JUSTDIVORCED 1 INTRODUCED
Table 1. Extracted events per template
Potential use cases for our constantly growing dataset include, but are not limited to, (breaking) news detection systems for news agencies, brand monitoring systems for so-called digital war rooms, but also more mundane use cases such as celebrity trackers (who married whom), or mashups in general. The dataset provides a comprehensible overview on usually rather complex data changes and may give valuable insights into dataset dynamics. Having stable identi ers for events further allows for interesting reasoning use cases.
Some information can simply not be deduced from discrete state resource descriptions, e. g. that a person moved from Germany to France can not be extracted from the separated facts that she lived in Germany and lives in France, rather both states need to be regarded and compared. This is what this project makes possible. The application supports an individual selection of changes of interest by the free de nition of digest templates, which allows monitoring customized data change events.